A number of readers have asked where the cover photo of our blog (above) was taken. Here is the story:

An old road above Leschi in Seattle switchbacks though an Olmsted Park, with a set of S-curves that we use for assessing a bike’s handling. It’s downhill, and with a bit of pedaling, you can build enough speed to make this truly challenging.

The first curve is an off-camber left with a decreasing radius (above). The best way around is cutting across the centerline in mid-corner once you get a clear sight line ahead. In the rare case that there is oncoming traffic, you get to test the brakes: Straighten the bike briefly while braking hard, then make a sharper turn at lower speed. Good brake modulation is key, so you can brake while the bike still is leaning into the curve.

If you rounded the left-hand curve at maximum speed, you immediately have to line up for the second curve. This right-hander is not particularly tricky, but the severe bumps make it crucial to pick a line close to the curb, where the pavement is a little smoother (above). For this, you need a bike that corners on a constant radius and can be placed on the road with precision.

Most modern racing bikes tend to drift outward once they are past the apex of the turn. In this corner, this puts you on the worst bumps. As you lose traction, you tend to run even wider and into the oncoming lane. This is a bad idea as a tunnel under an abandoned cablecar right-of-way obscures the occasional uphill traffic. In addition to precise handling, you want wide, supple tires for optimum traction on the bumpy pavement.

For the photo, the cornering was the easy part, as the low-trail MAP test bike with its 42 mm tires went exactly where I directed it. However, the digital camera we carried on this ride had a hard time focusing. We wanted a nice lean angle, which meant approaching the camera at considerable speed. We did a good number of runs, and in the end, only one photo was in focus, more through luck than anything else. (I wished I had brought my old Nikon with manual focus, which you focus on a crack in the pavement and then hit the shutter release when the rider arrives at that spot.) Fortunately, that one useful photo, taken by Hahn Rossman, turned out to be just about perfect.

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About Jan Heine, Editor, Bicycle Quarterly

I love cycling and bicycles, especially those that take us off the beaten path. I edit Bicycle Quarterly magazine, and occasionally write for other publications. One of our companies, Bicycle Quarterly Press publishes cycling books, while Compass Bicycles Ltd. makes and distributes high-quality bicycle components for real-world riders.

You said, “Most modern racing bikes tend to drift outward once they are past the apex of the turn.” Most racing bikes I’ve ridden have no clue when they’re past the apex of a turn. If a bike tends to drift outward after the apex of a corner, it’s probably because it’s being given input by the rider that causes it to do so, even if the rider doesn’t realize he’s giving it that input.

But I haven’t ridden a racing bike made more recently than 1985, so maybe modern racing bikes are more intelligent? ;)

It’s not that modern racing bikes “know” where the apex is, but they tend to fall into the corner. Then you correct, and the bike straightens. This is perfect for 90-degree corners, for example, in criterium races, where the bike rounds the corner with minimal input. However, it’s very hard to keep the bike on a constant radius, because it either falls into the corner or straightens, but never corners at “steady state.”

We’ve ridden other modern racing bikes in addition to the Trek and the Pegoretti you probably are referring to. In any case, we’ve found that front-end geometry determines a racing bike’s handling, and most modern racing bikes show relatively little variation (73-74 head angle, 39-45 mm fork offset).

The AF lock is useful, but it’s hard to focus on a not-yet-existing object with them…

That road is on my way to and from work- I hit it 3 or 4 days a week and on the way home (descending) I try to take it as fast as I can when it is dry. I don’t own a low trail bicycle- but on that particular road, because of the bumps, I can descend faster on my commuter with 35mm tires compared to my racing bike with 23mm tires. Just because the wider softer 35s stay in contact with the pavement better.

Those old twisty roads off of Lake Wa Boulevard never seem to get old and are the best part of my commute.

The most interesting thing about that photo, to me at least, is that you’re taking a turn during a high speed descent without transferring your weight to the outside pedal, (i.e., placing the center of gravity low and outside the center axis of the bike)–which seems to be a normal “best practice,” at least among the road racing community. Doesn’t taking the corner the way you’re taking it unnecessarily reduce traction and/or recourse if, say, you were to run into water or gravel near the apex of the turn?

I am not sure about “best practice,” but to me, the best practice is to remain centered and relaxed on the bike. I also need to suspend the bumps, so if I put one leg down, I’d have a harder time doing that.

Traction is the same, no matter whether you lean the bike more and your body less (as you suggest) or hang off the bike on the inside (as motorcycle racers do). Similarly, moving your inner knee into the curve only increases wind resistance, without any gains in cornering speed.

Good tires have a round profile, so it doesn’t matter on which part of the tread you roll. The forces care about where your center of gravity is, not where your body or your bike is. Your center of gravity leans as far as is required by the turn radius and speed, otherwise, you’d crash.

Being relaxed and centered on the bike allows me to make minute adjustments. It keeps the bike self-stable in mid-corner. (See the article on how bikes corner in Bicycle QuarterlyVol. 9, No. 2). Perhaps some steering geometries benefit from leaning the bike more than your body (as you do when you initiate a turn while riding no-hands), but a well-handling bike should not require this. Motorcycle racers have to move more, because their bikes are heavier than the riders… which isn’t much of an issue on a bicycle. (Motorcycle racers also feel the road with their knee pads, but bicycles don’t lean that far.)

True, but isn’t the OPERATIVE difference between the two cornering techniques this–that by corning with the outside pedal down and the rider’s weight on the outside pedal (meaning the rider is slightly raised off the saddle) that the center of gravity (and weight) is OUTSIDE the center line of the bike, vrs cornering with both pedals horizontal and the rider centered on the bike, the center of gravity (and weight) is either AT OR INSIDE the center line of the bike?

Between the two techniques, it’s been my experience that if traction is lost for some reason, with the center of gravity placed outside the center line of the bike, the rider is less likely to fall–the bike just sort of slides toward the outside of the turn with the rider remaining in control.

What matters is the center of gravity of bike and rider combined, not the centerline of the bike by itself. Imagine bike and rider as a unit (like the shadow outline half-way down on this page). Since the bike’s tires are round, it doesn’t matter at which angle they touch the road. Thus, the lean angle of the bike doesn’t matter (unless you try to pedal around the turn). What matters is the combined lean angle of rider and bike, i.e., how much the center of gravity is displaced sideways from the contact patch of the tires.

If you lose traction on dry pavement while cornering at the limit, you crash. I once actually did recover a slide on the rear wheel, but the side forces were too much for the (dishless) rear wheel. The rear wheel collapsed and I crashed anyhow. A modern 8-,9- or 10-speed wheel is much weaker laterally than the wheel on that bike…

Fortunately, the cornering limits are way higher than most cyclists realize. I was well within the limit in the photo…

They do, just a little slower. When I read Alex Stieda’s accounts of his time as a Tour de France racers, I was surprised to learn that descending on the limit was frowned upon. Races are not won on downhills, and as Bernard Hinault (or was it one of his “lieutenants”) pointed out to young Alex Stieda, there is no reason to risk you life on a descent.

That depends on many factors. Around a typical 90-degree criterium corner, racing bikes are no slower, and probably faster under most riders. Around a bumpy turn like the one in the photo, it’s a different story.

I’ve noticed how much faster Ryan now goes around these turns, since he switched from a carbon-fiber LeMond with 25 mm tires to a 650B Boulder Bicycle. Instantly, he was able to keep up through these corners. On his racing bike, try as he might, he lost 15 m (50 feet) through this section.